1. Field of the Invention
This invention relates to sine-function generators. More particularly, this invention relates to such generators producing an output signal having a precise sinusoidal relationship to analog input signals representing an input angle, and operable over a very large angular range, e.g. .+-.360.degree..
2. Description of the Prior Art
Many techniques have been used heretofore to generate an analog output signal having a sinusoidal relationship to an input signal representing an angle. Such prior techniques include piecewise linear approximations, polynomial and other continuous function techniques using multipliers, special translinear circuits, simple modifications of bipolar-transistor differential amplifiers, and circuits comprising large numbers of such differential amplifier stages connected in periodic antiphase.
With the exception of the last-mentioned, all of these approaches suffer from two limitations; first, they generally provide operation only over the angular range of .+-.90.degree. (some offer .+-.180.degree. range); second, they are usually of poor accuracy. The last-mentioned approach, as described by the present inventor in "Circuits for the Precise Synthesis of the Sine Function", in Electronic Letters, Vol. 13, Aug. 18, 1977, pp. 506, avoids these two limitations, but with a somewhat complex circuit. The present invention provides significantly greater simplicity and assured high performance in a practical commercial instrument.